not just culture but religion too makes a difference. Over here in Doha the majority of my friends who are in plural marriages and are truly happy with it all are American converts and as far as I know their culture far from embraces plural marriages as a norm.
On the other hand its also a personal feeling. I know of friends who are practicing Muslims but cannot handle their husbands taking other wives for various reasons and that too is just fine. Islamic-ally we are not under obligation to accept a co wife into our life. In fact we can even tell our husbands to be first off that we are not for it so he'd know better than sneaking any surprised suggestions later on. Bottom line is no one can be forced to do anything they do not want to do.
Personally I've NEVER had an issue with plural marriage though my family are not those who will ever see this as a norm and well and good. In fact my mom always says that should my hubby take another wife he will not be welcome in her home..I kid ya not! And my husband himself is not for it either cos most folks don't realize it but in a properly done Islamic polygyny marriage its mostly the men who are actually more taxed. Imagine having to maintain two households, so many kids, and be a good and fair husband and father at the same time and all the while working and earning a living..not easy by all means!